Antenna



Nov. 22, 1938. N. E. LlNDNBLAD 2 ANTENNA I Original Filed Sept. 7, 1928 4 Sheets- Sheet 1 IMPEDANCE mwrcwm I oswc: f

, INVENTOR. v I flis. LINDENBLAD- ATTORNEY.

E. LINDENBLAD ANTENNA Original "Filed Sept. 7, 1928 4 SheetsSheet 2 MPEzM/VcE [26 MA raw/1V6 DEV/CE 1 N x 22 I INVENTOR. N/LS .g/DENBLAD ATTORNEY.

' Nov. 22, 1938. N. 1-; LINDENBLAD 99 ANTENNA Original 'File d Sept. '7, 1928 4 Sheets-Sheet 5 TUNING Z2 /MEANS 5 IMPEDANCE wm TCH/NG MEA NS INV EN TOR.

N/LS E. L/NDENBL'AD ATTORNEY.

Nov. 22, 1938. E fl Re. 20,9 22

ANTENNA Original Filed Sept. 7. 1928 4 Sheets-Sheet 4 INVENTOR.

N/LS E. L/NDENBLAD ATTORNEY.

- Reissued Nov. 22, 1938 PATENT OFFICE ANTENNA Nils E. Lindenblad, Port Jeflerson, N. 1., assignor to Radio Corporation of America, a corporation of Delaware Original No. 1,884,006,

Serial No. 304,445, September 7, 1928.

dated 0mm- 25, 1932,

Application for reissue June 2, 1938, Serial No. 211,467

27 Claims.

This invention relates to antennae, and more particularly to directional antennae ior the propagation or reception of short wave signals.

Several types of beam and projector antenna systems for short waves have been developed, but these are rather complicated in structure and therefore relatively expensive to erect and adjust, and also are structurally suitable only for the wave length for which they have been designed and built. -It is the primary object of my invention to provide a simplified antenna which will be capable of accommodating a broad range of wave lengths, and to this end I have experimented very extensively with the problem of radiation from transmission lines, as a result of which I have devised an antenna consisting merely of simple linear conductors.

tenna is suitable both for transmission and reception, but for simplification I shall refer to transmission in the description which follows. Identical structure and theory may be applied to reception. T

It a standing wave is caused on a linear conductor which is long, relative to the working wave length, the conductor may be considered as composed of successive half wave length linear oscillators connected end to end, in which case there will be no summation of energy nor radiation in an end-on direction because each 0! the half wave oscillators does not radiate along its axis. Furthermore, there is little or'no radiation at right angles to the wire because although each half wave length oscillator might tend to radiate in this direction, the successive hali' wave length radiators are opposed in phase, so that at a distance from the wire the average eiiect .is small or zero. However, there is radiation in a direction intermediate the normal and longitudinal directions, and with a single conductor, this radiation takes place in the form of hollow cones having common axes in the wire. 7

This is wasteful of energy, and one object of my invention is to reduce the conical radiation so that it will consist only of concentrated lobes having axes in one plane.- This is accomplished by providing two collaterally spaced substantially parallel linear conductors which are long, relative to the working wave length, which are coupled in phase opposition, and which are so spaced apart as to concentrate the predominant radiation in the desired plane. Because of the opposed phase relation in the two conductors .there is substantially no radiation normal to the plane of the conductors. By spacing them a proper distance apart, the radiation from the The an pair or conductors is concentrated, essentially, into conjugate pairs or oppositely directed lobes the axes oi which lie in the plane of the conductors. 1

Thisarrangement, too, is wasteful of energy, and it is a further object of my invention to strengthen the radiation in one pair oi opposite critical directions, while weakening the radiation in the conjugate pair of opposite critical directions, which I do by staggering the pair oi wires. longitudinally, so that their ends make an angle with the transverse axis of the antenna equal to the critical angle of radiation, that is, the angle which the principal lobes of the radiation pattern oi! the antenna make with the longitudinal axis of the antenna. In this manner radiation in one pair oi opposite directions from each of the conductors come on the same wave front at the same time, but being opposite in phase, they neutralize and cancel each other. In the conjugate directions, owing to the physical displacement of the conductors, the radiated energy may be made to add. To make this addition a maximum it is desirable that the added energies be combined exactly in phase, and.to provide for this the spacing oi the pair oi wires should be such that the distance apart of corresponding points (such as the outer ends, illustrated as electrically open) on the two wires, measured in the direction of predominant radiation, is an odd number of halt wave lengths.

The radiation has so far been reduced to a bidirectional radiation, and a further object of my invention is to make it unidirective, for which purpose I provide another pair of simple linear conductors arranged to form another antenna Instead of forced feeding of energy to the secx and antenna a pure reflector action may be employed, in which case only one of the pairs of conductors is energized, in the case of a transmitter, or connected to the receiving set, in the insect a receiver, while the other pair of COD? doctors isproperly tuned and spaced and staggered so as to provide reflector action by reason or the energy transferred thereto from the other pair 01 conductors.

It has already been mentioned that a pair of conductors may be so .used as to cause the radiation to lie more nearly in a single plane, and in order to improve this-characteristic a number 56 i 2 of stories of antennae, such asI have already desc'ribed,may be employed, each antenna consisting or conductors lying in a single plane, while I the various antennae liein vertically spaced parallel planes, and are coupled together so as to operate electrically in parallel. The spacing of these, planes may be any spacing desired, particularly if a large number is used; but should preferably be a halt-wave length, many when only two antennae are used.

To sharpen the directivity in azimuth a number of'antennae may be used which are spaced apart in a horizontal direction, so as to praent a broadside array. 1

A further object ofmy invention is to elevate the propagated wave, and this may be done either by arranging the antenna system with the linear conductors spaced' apart, in a horizontal direction, but with their plane tilted upwards in the beused.

The invention is' described more in detail in the following specification, which is accompanied by drawings in which v tory of my inven- Figures 1 and 2are expl tion;

'FigureSrepresentsmyantennainsimplest form: I

Figure 4 represents a bidirective antenna constructed in accordance with my invention;

. Figure 5 is a unidirective antenna employing an energized reflector;

Figure 6 is a unidirective antenna employing a tuned reflector; 1

Figure 7 is a modification of Fig. 5;-

Flgure 8 indicates schematically an antenna system employing a plurality of antennae spaced vertically and horizontally to increase directivity in elevation and in azimuth, respectively;

Figure 91s a schematic representation .of'an antenna and reflector lying in a verticalplane to obtain elevated radiation; and

Figure 10 indicates schematically a broadside array of antennae lying in vertical planes to in crease the directivity in azimuth.

In Figure 1 there is shown a simple linear conductor 2 a half wave in length. The maximum radiation from this conductor takes place normally of the conductor, the pattern, in'section, being 2. figure 8 such as is indicated by the lobes When a conductor which is long, relative to the wave length, is employed, and a standing wave is caused thereon, the radiation normal of the conductor isopposed in phase in the successive half wave length portions of the conductor, and consequently there is little or no radiation normally of the wire. There is no radiation endwise oi the wire because although in this direction radiated energy would. add favorably, there is no radiated energy to be added. The radiation takes place in an intermediate direction. and the principal radiation is indicated in Figure 2, in which there is a long conductor 8, on which a standing wave is caused, and from this conductor radiation takes place inconical lobes, such as thelobes Ill and I2. Itwillbeseenfromtheflgurethattheselobes areintheformoi'hollow cones having their apices adjacent and located in the conductor. In actual practice it should be kept in mind that there willbe a number of diii'erent cones of various lesser magnitudes, and lying in different directions, relative. to the iongitudinal axis of the antenna, but for the sake of simplicity only the principal radiation is indicated, and its direction is indicated by the angle a; r a

Referring to Figure 3 it will be seenthat there are a paiLof long conductors l4 and i6, and

that these are substantially parallel and collaterally spaced. The conductors are connected in phase opposition to the transmitter 20 through tuning reactances 22, the latter being adjusted to cause standing waves on the conductors l4 and It by making the total electrical length of the circuit around the two wires a whole number of half wave lengths. This number should be odd, in order that the open ends of the conductors may be opposite in polarity. It should be noticedthat these wires preferably are left with openends, as a simple expedient to favor the growth of standing waves. If the transmission line 2 which interconnects the transmitter and the antenna is long, so that standing waves thereon might tend to cause undesired radiation, the transmission line may be closed with an impedance matching device. 28,. so that standing waves exist only between the device 26 and the antenna, and not on the line 2|.

In a direction normal to.'the plane of the conductors l4 and i6 radiation is cancelled because of the phase opposition of the energy in the conductors. -When the wires are properly spaced apart, the hollow cones of radiation indicated. in Figure 2 are reduced to four ears or lobes, the axes of which lie in' the plane of the conductors. These lobes may be grouped into the oppositely directed lobes 30 and 32, and a conjugate pair of oppositely directed lobes 34 and 36. The direction of radiation here also 'makes an angle a with the longitudinal axis of the antenna. A

Referring to Figure 4 it will be seen that the arrangement there disclosed is quite similar to that shown in Figure 3 except that the conductors l4 and I6 have been staggered, lcngitudinally, so that their ends make an angle a. with the transverse axis of the antenna. This causes the radiation corresponding to the lobes 3| and 3B in Figure 3 to come on the same wave front at the -same time, and being opposed in phase, the

radiation is practically cancelled, ,making the antenna bidirective, in the direction of the lobes 3| and I2, which are correspondingly strengththe two conductors will combine exactly in phase.

This spacing is indicated in Figure 4 in=terrns of the distance apart-namely. an odd number of half wave lengthsmeasured in the direction of predominant radiation-of corresponding points (such as the outer ends) on each wire. In the formulae given in connection with Figures 4, 5, and '1 oi the drawings, n is zero or any whole number and x is the operating wave length.

It is slightly desirable, but not essential, that the spacing D be one or more whole wave lengths,

in which case radiation transversely of the antenna will be effectually prevented, but this con-.

dition can only be met for certain special cases of the angle a, and is not important, owing to the fact that each wire is essentially non-radiative in a normal direction.

Referring now to Figure it will be seen that there are two pairs of collaterally spaced conductors, l4, l6 and H4, H6, and each of these pairs is arranged in accordance with the principles set forth in connection with Figure 4. The pairs of antennae are energized in parallel through a. branched transmission line system, and the feed is made such that the antennae are energized in phase quadrature. This may be obtained most simply by having the arms of the branched transmission-line differ, in length byan odd number of quarter wave lengths, as has been indicated in the drawings, this difference in length being introduced ahead of the impedance matching devices, so that it exists in lines on whichthere is a travelling wave, rather than a standing wave.

The pairs of conductors are spaced apart a distance d, and this distance is such that when multiplied by the cosecant of the angle of principal radiation or, the product will be an odd num ber of quarter wave lengths, so that owing to the initial phase difference in the energization of the antennae, the radiated energy in one of the opposite directions, as 30, adds, while in the opposite direction the energies are opposed, and cancel, thereby making the antenna unidirective, instead of bidirective.

The arrangement shown in Figure 5 employs an energized or forced feed reflector, which may be called a director, but it is 'alsopossible to use a simple tuned reflector energized from the other pair of conductors. In this case it is desirable to have the reflector near the energized conductors, and in such case the arrangement preferably is slightly modified as in Figure 6, in which the pair of conductors i4 and I6 corre sponds to the similarly numbered pair in the preceding figureavwhile the appropriate reflector wires are numbered 2l4 and 2I6. As before, the ends of the conductors l4 and ii are staggered I so as to make an angle a with the transverse axisof the antenna, and the same applies to the reflecting conductors 2 and MG. Also, as before, the distance D is so chosen that when multiplied by the sine of the angle on the product will equal an odd number of quarter wave lengths, so that radiation in the direction of principal radiation will be added as nearly as possible in phase, and furthermore, the distance D may, if desired, be made one or more whole wave lengths'where the angle it permits this positioning. The conductors i4 and IG are energized in phase opposition from a transmitter II,

and if desired, an impedance matching device 16, and tuning means 22, may be employed. The conductors 2 l4 and iii are coupled in phase opposition. and are provided ,with a tuning means 222, here illustrated as a trombone slide, so that the reflector may be tuned to favor the production of standing waves.

The problem of the spacing and of the stagger of the reflector conductors, relative to the conductors i4 and I6, is not so simple as in the preceding case. If energywere induced in the conductor 2 is, from the conductor l6, only along the line of direction of principal radiation, as indicated by the dotted arrow 40, the rule would be to make this distance a quarter wave, so that the reflected energy would combine in phase with the energy radiated from'the conductor It in one tion. The situation is complicated by the fact that energy is induced in the conductor 2 l6 from the conductor is along the shorter normal path, indicated by the arrow 42, and from the conductor l4, indicated by the arrow 44, so thatthe phase and magnitude of the current in the reflector is the resultant of several factors. The best arrangement may be found by experiment.

In Figure '7 there is an energized director H4, 6, as in Fig. 5, but the spacing d between the antenna and the director antenna is made less than the spacing D between the conductors of the antennae as in Fig. 6; Another feature of this modification is the use of the trombone slides 46 and 48 totune the antennae. This tuning need not be great in range, though the antenna structure will cover a great wave length range, because the adjustment can be made for a difierent number of half waves in length, whenever necessary to accommodate a desired wave length. The transmitter 20 is coupled to the antennae through a'transmission line 24, which is coupled to the trombone slide 46 at points so spaced that the impedance of the line is matched. The trombones' 46 are interconnected by a line 90, the ends of which are coupled to the trombone slides at points so spaced that the impedance of the line is matched, so that there is a travelling rather than a standing wave on the The conductors H4 and H6 are lengthenedby the addition of the loops 94 and 98, so as to equal the conductors l4 and IS in length. With this precaution the antennae should both take equal current. Ammeters 98, shunted to the trombone slides 46, are made to read alike, and

' at a maximum, when the antenna is properly adjusted.

, direction, and out of phase in the opposite direc- In connection with Figure 3, and the succeeding figures, it has been pointed out that the radiation takes place principally in the plane of the conductors, and in order to sharpen this characteristic antennae, such as have already been described. may be located above one another in parallel planes, so as to make a multiple storied antenna. This has been indicated in A, of Figure 8, in which an entire antenna,-consisting of a pair of conductors, and either an energized or non-energized pair of reflecting conductors, properly staggered, and lying in a single plane, is

schematically indicated by the U shaped line ill.

Another such antenna system, lying ina parallel plane, is indicated at 52, and these are fed electrically in parallel through a branched transmission line system. schematically indicated by the single lines 54, 5B and 8. The spacing should preferably be a half or odd number of half wave lengths. so as to provide complete canthis type of antenna the structure is arranged at an angle a, in azimuth, relative to the direction in which radiation is desired. If it is desired to sharpen the'directivit'y in this direction,

1. e. in az muth, a plurality of antennae may be.

, cellation in an up and down direction. Withwhich each antenna lies must be correspondingly tilted or elevated away from a truly horizontal direction. The'antennae so far described provide horizontal polarization.

By positioning the plane of an antenna consisting of two pairs or conductors, such as has already been described in connection with Figures 5, 6, and 7, in a vertical plane, as is indicated in Figure 9, radiation with vertical polarization may be provided. In this case the antenna is directed in the direction of desired propagation in azimuth, and the angle it provides the angle of elevation. This arrangement is desirable because the elevated radiation is obtained without the expense of an elaborate supporting structure for holding'the antenna at the corresponding angle. Slight changes in the angle of elevation may be made by slightly changing the position 01 the conductors, relative to the horizontal, while keeping them in a vertical plane.

In order to sharpen the directivity in azimuth a number of antennae, located in parallel planes, may be provided as has been indicated in Figure 10, in which each of the antennae 10, 12, and 14 is an antenna such as has been described in either of Figures 5, 6, or '7, and the various antennae are energized electrically in parallel through a branched transmission line system I6, 18, 80. The branches are so arranged that the antennae are energized cophasially, and the antennae are preferably spaced ahalf wave apart,

t may be at any spacing, esp cially when a considerable number antennae are employed. This antenna system propagates a vertically polarized elevated wave.

Over a considerable range of tuning the angle a remains quite constant. Only by changing the wave length so greatly that the character of the long wire is completely changed so as to be a relatively few instead of many waves in length; does that lobe'of radiation which is greatest in magnitude shift or jump from one to another, so as to definitely and considerably change the angie of radiation is. For example, using conductors approximately eight mean waves in length I have varied the tuning from about five to seven meters without appreciably changing the angle of radiation. The antenna is tuned, but the antenna structure itself need not be changed. The tuning is small in amount because it is needed only to bring the total electrical length to the nearest odd number of half waves, rather than to a fixed length.

I claim:

1. A directional antenna comprising a collatera-lly spaced pair of s mple linear conductors adapted to have standing waves formed thereon which are long, relative to the working wave length, and means energizing said conductors in phase opposition at adjacent ends of said conductors, said-conductors lying on thesame side of said energizing means and extending away from said energizing means whereby radiant action occurs predominantly in a direction making equal angles greater than zero degrees with reference to said conductors.

2. A directional antenna comprising a collaterally spaced pair of substantially parallel simple linear conductors adapted to have standing waves formed thereon which are long, relative to the working wave length, and means encrgizing said conductors in phase opposition, said conductors lying on one side of and extending away from said energizing means, radiant action occurring predominantly in a direction making equal angles greater than zero degrees with re!- erence to said conductors.

3. A directional antenna comprising a collaterally spaced pair or substantially parallel simple linear conductors which are long, relative to the working wave length, means coupling said conductors in phase opposition, and means for tuning said conductors and coupling means to an overall electrical length an odd number of half waves, so as to cause standing waves of opposite polarity on the conductors.

4. A directional antenna comprising a collaterally spaced pair 01 simple linear conductors which are long, relative to. the working wave length, and which are so staggered, longitudinaldirections is weakened, means coupling said conductors in phase opposition, and means tor tuning said conductors and coupling means to an overall electrical length of an odd number of half waves, so as to cause standing waves of opposite polarity on the conductors.

6. A directional antenna comprising two pairs 01' collaterally spaced simple linear conductors all lying in the same plane, the conductors in each of said pairs of conductors being long, relative to the working wave length, and so staggered, longitudinally, that radiation in one pair of opposite critical directions is strengthened, while radiation in the conjugate pair of opposite critical directions is weakened, said pairs of conductors being so staggered and spaced apart in the direction of principal radiation as to make the antenna unidirectional, means coupling the pairs of conductors in phase opposition, and means coupling at least one of the pairs of conductors with radio radiation in one pair of opposite critical direc tions is strengthened, while radiation in the conjugate pair of opposite critical directions is weakened, means coupling the conductors in each pair in phase opposition, means for tuning said conductors and coupling means to an overall electrical length of an odd' number of half waves, so as to cause standing waves of opposite polarity on the conductors in each pair, said pairs oi. conductors being so spaced apart in the direction of principal radiation as t0 ma'..e the antenna unidirective, and means coupling at least one of the pairs of conductors with radio equipment.

8. A directional antenna system comprising two pairs of collaterally spaced and substantially horizontal parallel simple linear conductors all lying in the same vertical plane, each conductor being long relative to the working wave length, the conductors in each pair being so staggered, longitudinally, that radiation in one pair oi opposite critical directions is strensthened, while radiation in the conjugate pair of opposite critical directions is weakened, means coupling the conductors in each pair in phase opposition, means for tuning said conductors and coupling means to an overall electrical length of an odd number of half waves, so as to cause standing waves of opposite polarity on the, conductors in each pair, said pairs of conductors being so spaced apart in the direction of desired radiant action as to make the antenna unidirective, and means coupling at least one of the pairs of conductors with radio equipment.

9. A directive transmission system comprising two pairs of collaterally spaced simple linear conductors all lying in the same plane, the conductors in each of said pairs of conductors being long, relative to the working wave length, and so staggered, longitudinally, that radiation in one pair of oppos te critical directions is strengthened, while radiation in the conjugate pair of Opp site critical directions is weakened, said pairs conductors being so staggered and spaced apart in the directional principal radiation as to make the antenna unidirectional, means coupling the pairs of conductors in phase opposition, a radio transmitter for energizing the con-' ductors, and means coupling the transmitter to at least one of the pairs of conductors in phase opposition.

' 10. A directive transmission system comprising two pairs of collaterally spaced and. substantially parallel simple linear conductors all lying in the same plane, each conductor being long, relative to-the working wave length, the con-- ductors in each pair being, so staggered, longitudinally, that radiation in one pair of opposite critical directions is strengthened, while radiation in the conjugate pair of opposite critical directions is weakened, means coupling the conductors in each pair in phase opposition, means for tuning said conductors and coupling meansto an overall electrical length of an odd number of half waves, so as to cause standing waves of opposite polarity on the conductors in each pair, said pairs of conductors being so spaced apart in the direction 0! principal radiation as to make the'antenna unidirective, a radio transmitter for energizing the conductors, and means coupling the transmitter to said pairs of conductors in phase quadrature. I

11. A directional antenna syst-,m including a plurality of unidirectional antennae lying in.

spaced parallel planes, each antenna comprising two-pairs of collaterally spaced and substantially parallel simple linear conductors lying in a single plane, the conductors being long, relative to the working wave length. the conductors in each of said pairs being so staggered, longitudinally,

that radiation in one pair of opposite critical directions is strengthened, while radiation in the conjugate pair of opposite critical directions is weakened, means coupling the conductors in each pair in phase opposition, means for tuning said conductors and coupling means to. an overall electrical length oi'an odd number of ball waves, so as to cause standing waves of opposite polarity on the conductors in each pair, said pairs of conductors being so staggered and spaced apart in the direction 01' principal radiation as to make the antenna unidirectional, and means coupling corresponding pair otconductors in each of the antenna? in parallel and in proper phase to radio equipment.

12. A unidirectional antenna system includductors being long relative to the working wave length, the conductors in each of said pairs being so staggered, longitudinally, that radiation in one pair of opposite critical directions is strengthened, while radiation in the conjugate pair of opposite critical directions is weakened, means coupling the conductors in each pair in phase. opposition, means for tuning said conductors and coupling means to an overall electrical length of an odd number of hall waves, so as to cause standing waves of opposite polarity on the conductors in each pair, said pairs of conductors being so staggered and spaced apart in the direction of principal radiation as to make the antenna unidirectional, and means coupling corresponding pairs of conductors in each of the antenna in parallel and in proper phase to radio equipment.

13. A directive transmission system including a plurality of unidirective antennae lying in spaced parallel planes, each antenna comprising two pairs of collaterally spaced and substantially parallel simple linear conductors lying in a single plane, the conductors being long, nelative to the working wave length, the conductors in each' of said pairs being so-staggered, longitudinally, that radiation in one pair oi opposite critical directions is strengthened, while radiation in the conjugate pair of opposite critical directions is weakened, means coupling the conductors in each pair in phase opposition, means for tuning said conductors and coupling means to an overall electrical length 01 an odd number of half waves, so as to cause standing waves of opposite polarity on the conductors in each pair, said pairs of concoupling pairs of the wires in phase oppositiom means ior tuning the pairs of wires to an odd number or half waves in total electrical length so as to cause standing waves of opposite polarity thereon, the wires in each pair being so staggered longitudinally that their ends form the same angle, relative to the transverse axis of the antenna, that the direction of principal radiation makes with the longitudinal axis of the antenna, and so spaced apart that corresponding points on the two wires-oi each pair are separated by an odd number of half wave lengths in the direc-- tion of principal radiation, the pairs of conductors being so stag ered and spaced apartthat energy from one pair combines with the energy from the other pair in phase so as to make the antenna unidirectional, and radio equipment coupled. to at least one of the pairs of conductors.

15. A unidirectional short wave antenna comprising four collaterally spaced substantially parallel wires which are long, relative to the working g wa've length, all lying in a single plane, a pair of trombone slides for coupling together pairs of the wires and for tuning them to an odd number of half waves in total electrical length so as to cause standing waves of opposite polarity thereon, the wires in each pair being so staggered longitudinally that their ends form the same angle, relative to the transverse axis of the antenna, that the direction of principal radiation makes with the longitudinal axis of the antenna, and so spaced apart that corresponding points on the two wires of each pair are separated by an odd number of half'wave lengths in the direction of principal radiation, the pairs of conductors being spaced apart a quarter wave length in the direction of principal radiation, a transmission line a quarter wave in length coupled to the trombone slides at points so spaced that the impedance therebetween matches the impedance of the transmission line, and radio equipment coupled to one of the trombone slides.

16. A directional antenna comprising a collaterally spaced pair of simple linear conductors which are long, relative to the working wave length, and which are so staggered, longitudinally that wave action in one pair of opposite critical directions is strengthened, while wave action in the conjugate pair of opposite critical directions is weakened, and means for energizing said wires in phase opposition.

1'7. A directional antenna comprising a col-- rsite critical directions is weakened, said wires adapted to be energized in phase opposition.

18. A directional antenna comprising a collaterally spaced pair of substantially parallel simple linear conductors which are long, relative to the working wave length, and which are so staggered, longitudinally, that wave action in one pair of opposite critical directions is strengthened, while wave action in the conjugate pair of opposite critical directions is weakened, said conductors adapted to be energized in phase opposition, means for actionally coupling the conductors, and meansfor tuning said conductors and coupling means to an overall electrical length of an odd number of half waves, so as to cause standing'waves of opposite polarity on the conductors.

19. A directional antenna comprising two pairs of collaterally spaced simple linear conductors all lying in the same plane, the conductors in each of said pairs of conductors being long, relative to 20. A directional antenna system comprising two pairs of collaterally spaced and substantially parallel simple linear conductors all lying in the same plane, each conductor being long, relative to the working wave length, the conductors in each pair being so stagg red, longitudinally, that radiant action in one pair of opposite critical directions is strengthened, while radiant action in the conjugate pair of opposite critical directions is weakened, means coupling the conductors in each pair in phase opposition, means for tuning said conductors and coupling means to an overall electrical length of an odd number of half waves, so as to cause standing waves of opposite polarity on the conductors in each pair, said pairs of conductors being so spaced apart in the direction of desired radiant action as to make the antenna unldirective, and means coupling at least one of the pair of conductors with radio apparatus.

21. A directional antenna comprising a pair of long linear wires connected at adjacent ends to high frequency apparatus and having standing waves of opposite instantaneous polarity thereon, said wires being several wave lengths in length and extending away from andon one side only of .said adjacent ends.

22. A directional antenna system comprising a pair of long straight wires and means at adjacent ends of the wires for exciting the wires in phase oppositionwhereby standing waves of opposite instantaneous polarity are set up on the wires, said wires being several wave lengths'in length at the operating frequency and extending on one side only and away from said adjacent ends.

23. A directive antenna system for propagating or receiving propagated electro-magnetic waves comprising a pair of substantially straight conductors, long, relative to the working wave length such that several standing waves at the operating frequency are set up on each conductor, said conductors being arranged so that radiant action occurs in a direction making the same angle with each conductor, and means coupling said conductors in phase opposition, said conductors lying in the same plane and extending away from said coupling means on one side only thereof.

24. A directive antenna system for propagating or receiving electromagnetic waves as claimed in claim 23 wherein a similar pair of conductors is provided, the conductors of said similar pair being I effect of the system is augmente 26. A directive antenna system for propagating or receiving electromagnetic waves as claimed in claim 23 wherein a similar pair of conductors is provided, the conductors of said similar pair being arranged parallel to the respective conductors of the first pair and lying in a plane parallel to the plane of said first pair whereby the directional efiect of the system is augmented.

27. A directive antenna system for propagating or receiving propagated electromagnetic waves, comprising a plurality of pairs of conductors arranged in the same plane, respective conductors of the pairs being substantially parallel, each of said conductors being long relative to the working waves length and adapted to have a plurality of standing waves at the working wave length set up thereon, means for connecting the conductors of each pair in phase opposition, the conductors of each pair extending on one side only and away from said connectingmeans, and, a like number of pairs of conductors arranged in a plane par;

allel to the plane of said first mentioned plurality of pairs of conductors, the conductors in the like plurality of pairs being arranged parallel to the conductors of said first mentioned plurality of pairs, the conductors of said like pairs being coupled and arranged in a manner similar to the conductors of said first mentioned pairs of conductors, like conductors of the pairs being arranged in parallel fashion, whereby radiant. ac-

tion occurs predominantly in a direction making equal angles greater than zero degrees with each conductor of said system.

Nit-s E. LINDENBLAD. 

